Structure Design And System Control Of Ellipsometry Based On Single Motor Driven Rotating Double Compensator

With the development of nano-optical measurement technology,ellipsometry technology that can realize non-contact,non-destructive,fast and even dynamic measurement of samples has been widely used.The synchronous rotation control of the detector is complex,and the triggering and acquisition of the detector synchronization signal is difficult,and the long-term running stability is poor.A rotation structure and control method of a dual-phase compensator driven by a single motor are proposed.In this structure,the diameter ratio of the synchronous gear connected to the servo motor is 5:3.Different gear diameters are used to realize the differential speed control of the double rotary compensator.Combined with the theory of ellipsometry measurement of the double rotary compensator,the multi-dimensional sample can be realized.Information acquisition;and based on control theory,a high-performance microDSP control chip is used as the design core,the main control circuit and the servo motor drive circuit are designed,and the relevant hardware modules are completed.Finally,the speed of the compensator is stable and controllable during the long-term operation of the system,and 16 parameters of the Mueller matrix can be obtained in one measurement,which provides theoretical basis and technical support for the information of each dimension of the ellipsometry sample.The main research work of this paper includes the following aspects:Firstly,the principle of Mueller matrix ellipsometry is introduced,combined with the double rotating compensator ellipsometry technology,the characteristics of double phase rotating compensator ellipsometry and the Mueller matrix measuring theory are analyzed in detail,and the Mueller matrix ellipsometry is completed.The optical path structure design of the measurement experimental platform.Secondly,the hardware structure of the ellipsometry system is designed,and a rotating structure design of double compensators driven by a single motor is proposed,which can realize the 5:3 synchronous rotation of double compensators driven by a single motor,and reduce the hardware circuit design and synchronization data.Difficulty of collection.According to the actual needs of the project,a variable-angle experimental measurement platform is designed,and the optical components on the polarizing arm and the analyzer arm are integrated and designed.On the basis of the optical path design,the selected optical components are packaged and placed.Finally,the hardware control circuit is mainly designed.The design mainly includes two modules,the main control board hardware module and the servo motor drive module.The design of the hardware circuit of the main control board is mainly based on the DSP28335 chip and related external circuits.It is mainly responsible for the communication with the upper computer,debugging and downloading programs,outputting PWM pulses,encoder position detection and other functions.At the same time,the working principle and vector control strategy of the servo motor are introduced.The design of the servo motor drive module is mainly based on the IR2136 S chip,which is mainly responsible for driving the motor to drive the load,including voltage conversion circuit,drive circuit,encoder signal processing circuit,etc.Finally,the simulation model of the permanent magnet synchronous motor control system is established in the MATLAB/Simulink environment,and the actual parameters of the motor are set,and a set of stable and reliable proportional,integral and derivative parameters is debugged.Then the experimental platform is built,the hardware structure of the dual-rotation compensator is tested,and finally the ellipsometry system is integrated and debugged and tested.